22 



NATURE 



[May 5, 1892 



moves for comparatively long times in lines very approximately 

 straight, and experiences changes of velocity and direction in 

 comparatively short times of collision — and it is only for the 

 kinetic energy of the translatory motions of the molecules of the 

 "perfect gas," that the temperature is equal to the average 

 kinetic energy per molecule, as first assumed by Waterston, and 

 afterwards by Joule, and first proved by Maxwell. 



"Researches on Turacin, an Animal Pigment containing 

 Copper ; Part II." By A. H. Church, M.A., F.R.S., Pro- 

 fessor of Chemistry in the Royal Academy of Arts, London. 



This paper is in continuation of one read before the Society 

 in May 1869 (Hhil. Trans., vol. clix. pp. 627-36). It con- 

 tains an account of observations made by other investigators on 

 turacin and on the occurrence of copper in animals ; a table of 

 the geographical distribution of the Touracos, and a list of the 

 twenty-five known species ; a chart of turacin spectra (for which 

 the author is indebted to the kindness of Dr. MacMunn) ; and 

 a further examination of the chemical characters and the compo- 

 sition of turacin. The more important positions established by 

 the present inquiry are these : — 



1. The constant occurrence in eighteen out of the twenty-five 

 known species of MusophagidcE, of a definite organic pigment 

 containing, as an essential constituent, about 7 per cent, of copper. 



2. The " turacin-bearers" comprise all the known species of 

 the three genera, Turactis, Gallirex, and Miisophaga ; while from 

 all the species of the three remaining genera of the family Muso- 

 phagida—wzmfiXy, Corythaola, Schizorhis, and Gymnoschizorhis 

 — turacin is absent. Furthermore, the zoological arrangement 

 of the genera constituting this family is in accord with that 

 founded on the presence of turacin. 



3. The spectrum of turacin in alkaline solution shows, be- 

 sides the two dark absorption bands previously" figured, a faint 

 broad band on either side of line F, and extending from \ 496 

 to A 475. 



4. The spectrum of isolated turacin in ammoniacal solution 

 shows, besides the three bands already named, a narrow fourth 

 band, lying on the less-refrangible side of line D, and extending 

 from A 605 to A 589. It probably arises from the presence of 

 traces of the green alteration-product of turacin formed during 

 the preparation of that pigment in the isolated condition ; an 

 alteration-product which is likely to prove identical with 

 Krukenberg's turacoverdin. 



5. Turacin in ammoniacal solution remains unchanged after the 

 lapse of twenty-three years. 



6. Turacin in the dry state, when suddenly and strongly 

 heated, yields a volatile copper-containing red derivative, which, 

 though undissolved by weak ammonia-water, is not only soluble 

 in, but may be crystallized from, ether. 



f- 7. Turacin in the dry state, when heated in a tube surrounded 

 by the vapour of boiling mercury, becomes black, gives off no 

 visible vapour, is rendered insoluble in alkaline liquids, and is 

 so profoundly changed that it evolves no visible vapour when 

 afterwards strongly heated. 



8. The accurate analysis of turacin offers great difficulty. 

 The percentage composition, as deduced from those determi- 

 nations which seem most trustworthy, is — 



Carbon 53'69 



Hydrogen 4'6o 



Copper 7'Oi 



Nitrogen ... 6*96 



Oxygen 2774 



These numbers correspond closely with those demanded by 

 the empirical formula CgjHgiCujjNgOgo, although the author 

 lays no stress upon this expression. 



9. Turacin presents some analogies with hrematin, and yields, 

 by solution in oil of vitriol, a coloured derivative, turaco- 

 porphyrin. The spectra of this derivative, both in acid and 

 alkaline solution, present striking resemblances to those of 

 haematoporphyrin, the corresponding derivative of h?ematin. 

 But copper is present in the derivative of turacin, while iron is 

 absent from its supposed analogue, the derivative of haematin. 



Chemical Society, April 7.— Dr. W. H. Perkin, F.R.S., 

 Vice-President, in the chair. — The following papers were 

 read : — The separation of arsenic, antimony, and tin, by 

 J. Clark. The mixed sulphides of arsenic, antimony, and 

 tin obtained in the ordinary course of quantitative analysis 

 are dissolved in a strong solution of ferric chlotide in hydro- 

 chloric acid, and the arsenic distilled off and weighed as 

 trisulphide. The residual liquor contains the antimony as 



NO. II 75 VOL. 46J 



trichloride, and the tin as stannic chloride, together with 

 ferrous and ferric chlorides. Without removing the iron salts, 

 the antimony is precipitated with hydrogen sulphide in a 

 tepid solution containing from one-quarter to one-third of its 

 volume of hydrochloric acid and a considerable quantity of 

 oxalic acid. The precipitate, which is free from tin, is washed 

 first with water, then with alcohol, and finally with carbon 

 disulphide, and weighed as SbjSa after being dried at 130". 

 When the antimony precipitate is large, it must, after drying, 

 be digested in carbon disulphide to extract the whole of the 

 sulphur. To obviate this, the author reduces the excess of 

 ferric chloride with thin sheet- iron, as soon as the yellow 

 colour has disappeared the undissolved iron is removed, and the 

 antimony which has come down is redissolved by cautiously add- 

 ing ferric chloride till the solution is distinctly yellow, showing that 

 all the tin is in the stannic state ; a warm solution of oxalic acid 

 containing about one-third of its volume of hydrochloric acid is 

 then added, and the pi-ecipitated antimony trisulphide washed 

 and weighed as "above. After removal of the antimony, the 

 hydrogen sulphide is expelled by boiling, the oxalic acid decom- 

 posed with potassium permanganate, the tin precipitated in a 

 hot solution with hydrogen sulphide, and allowed to stand till 

 cold. The stannic sulphide thus obtained is filtered, washed, 

 ignited, and weighed as SnOj. — Platinous chloride and its use as 

 a source of chlorine, by W. A. Shenstone and C. R. Beck. 

 The authors have examined chlorine prepared from six specimens 

 of platinous chloride of independent origin, and have found 

 oxygen and hydrogen chloride to be present in them all. From 

 these results they conclude that platinous chloride made by any 

 of the processes hitherto recommended, including that lately 

 suggested by L. Pigeon, contains a very perceptible quantity of 

 some basic compound, which gives off water, together with the 

 gases previously mentioned. It was also noticed that after 

 mercury has been exposed to the action of chlorine, in the 

 presence of a trace of water, it becomes capable of absorbing 

 hydrogen chloride ; it is not yet certain whether this action i 

 depends on the presence of oxygen or not. — Note on the ad- 

 hesion of mercury to glass in the presence of halogens, by W. A. 

 Shenstone. The author finds that carefully purified chlorine» .. 

 bromine, and iodine affect mercury like ozone, causing it to 

 adhere to glass in a remarkably perfect manner. — The decom- 

 position of mannitol and dextrose by the Bacillus ethaceticus, 

 by P. F. Frankland and J. S. Lumsden. The authors find that 

 the products of fermentation of both mannitol and dextrose by 

 B. ethaceticus consist of ethyl alcohol, acetic acid, carbon 

 dioxide, hydrogen, and traces of succinic acid. A considerable 

 quantity of formic acid is also formed when the fermentation 

 proceeds in a closed space, whilst, in fermentations conducted in 

 flasks merely plugged with cotton wool, formic acid, except in 

 traces, is an exceptional product. This phenomenon has pre- 

 viously been found to occur with fermentations by means of B. 

 ethacctosuccinicus. I^"ormic acid is doubtless a primary product 

 of the fermentation, but tends to break down into carbon dioxide 

 and hydrogen. In the closed space, however, equilibrium is 

 soon established between the formic acid and its decomposition 

 products, and part of the formic acid is subsequently found in 

 the solution. This view is supported by the fact that carbon 

 dioxide and hydrogen are found in almost equal volumes. 

 The proportions in which the several products are obtained 

 from mannitol are approximately represented by the equation— 

 3C6H14O6 + H.O = C2H4O2 + SCoHyO + 5CH,Oo + CO.. 

 In the case of dextrose the products occur in the proportions : 

 2-5C2H«0 : I -sC-.H^Oj : 3CH.P.2 : COj. There is a close quali- 

 tative and quantitative resemblance between fermentations by B. 

 ethaceticus and those occurring by means of the Pnciimococcus 

 (FriedlJinder), which renders it probable that this ethacelic decom- 

 position is a very general and typical form of fermentative change. 

 — The preparation of glycollic acid, by H. G. Colman. Glycollic 

 acid may be readily prepared by boiling concentrated potas- 

 sium chloracetate solution for 24-30 hours. The liquid is then 

 distilled under reduced pressure, and the residue mixed with 

 acetone. On evaporation of the filtered solution, glycollic acid 

 crystallizes out in colourless crystals, containing only about 0'5 

 per cent, of ash. This acid would seem to be dimorphous. 

 Glycollic anilide may be prepared by heating glycollic acid 

 for some time to 240", and boiling the product wuh aniline. — 

 Researches on silicon compounds and iheir derivatives ; Part 

 vi. The action of silicon tetrachloride on substituted phenyl- 

 amines, by J. E. Reynolds. Diphenylamine combines with 

 silicon tetrachloride to form an unstable addition compound, 



